Why Is Altruistic Behaviour Problematic for the Theory of Natural Selection?

Nice guys finish first, a chapter title in R. Dawkins' revolutionary popular science book the Selfish Gene. Although true altruism can not exist according to the classical theory of natural selection if such an evolutionary protagonist as RD has time for it, then there must be a good reason. In fact, we see much behaviour in nature that appears altruistic: alarm calling, guarding, defence and foraging by non-reproductives and grooming are just a few examples. Since work first began on altruistic behaviours, various mechanisms have emerged that have been able to squeeze them into the conventional model of natural selection. However, by no means can all altruistic behaviour now be explained by these methods.

First, altruism must be defined so we can see how it defies the conventional theory of natural selection. Perhaps more importantly we must then ask why, when inexplicable using Darwin's original model for selection, we still frequently observe altruism in nature. Three answers to this question have been put forward: kin selection, group selection and reciprocation. These will be examined in order.

When an actor's behaviour increases the fitness of the behaviour's receiver at the expense of the actor, then the behaviour is said to be altruistic. This definition is simplistic but provides a good starting point; throughout the discussion it will be sharpened. In contrast to so-called selfish behaviour increases the actor's fitness while reducing the fitness of the receiver. If both the actor and the receiver gain in fitness following a behaviour, then the behaviour is cooperative. We must keep in mind that these costs and benefits are measures of reproductive success, the number of offspring surviving to reproductive age and thus the number of genes passed to the next generation.

It is worth mentioning that much altruistic behaviour may directly benefit those performing the behaviour in a way that may not be immediately obvious to the observer. Guard watches in meerkats may be an example of this. It was always assumed that meerkats guards were giving up valuable foraging time to watch for predators to the benefit of their group. However, it has recently been suggested that in fact they only take turns on guard when they are not hungry and thus they gain a significant head start in the escape if they are the first to spot the predator. They also tend to guard while positioned close to their bolt hole, giving them yet more of an increased chance of escaping the predator relative to the other members of their group. Rhesus monkey (Macaca mulatta) allomothers provide another such example: the behaviour that was originally thought to be purely altruistic is now thought to directly benefit the allomothers, as when it come to their own reproduction they have had experience in offspring care. These behaviours can therefore be classified as selfish.

Why a gene encoding truly altruistic behaviour can not be selected for seems intuitively obvious: by its own action it will decrease its frequency in the population by decreasing the fitness of those who carry it. It will also increase the fitness of other members of the population who may not carry the same gene. Why then do we still see so many animals committing suicide, giving up time, effort and reproduction for the sake of other individuals? So far the most convincing answer and certainly the one with most supporting evidence is kin selection.

Kin selection does not contradict the conventional natural selection but rather applies a filter to its perspective, changing it from a view of selection based on the level of the individual to one based on the level of the gene. It states that individuals gain indirect' fitness benefits, coined originally by Hamilton, through the survival and reproduction of nondescendent offspring. These can even be quantified using r, the coefficient of relatedness. r for a brother, for example, is 1/2, as brothers share on average...

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Naturalselection: A process in which results in the characteristics of a population of organisms change over many generations. It occurs because individuals with certain inherited traits survive specific local environmental conditions and through reproduction, pass on their alleles to their offspring.
Selective Pressure: environmental conditions that select for certain characteristics of an individual and select against other characteristics
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They were able to survive the environmental change around them, and thus through reproduction passed on their genetic information against resistances to a particular antibiotic to their offspring’s.
NaturalSelection is Situational
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A trait that was once not used as an advantage for survival may be used in different times and situations for survival and reproduction
Fitness: the ability for an organism to survive and reproduce offspring’s that will live long enough to reproduce. The contribution to the gene pool of the next generation by producing offspring’s that survive long enough to reproduce
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